Innate immune sensing of modified vaccinia virus Ankara (MVA) is mediated by TLR2-TLR6, MDA-5 and the NALP3 inflammasome

Department of Medicine, Infectious Diseases Service, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland.
PLoS Pathogens (Impact Factor: 7.56). 07/2009; 5(6):e1000480. DOI: 10.1371/journal.ppat.1000480
Source: PubMed


Modified vaccinia virus Ankara (MVA) is an attenuated double-stranded DNA poxvirus currently developed as a vaccine vector against HIV/AIDS. Profiling of the innate immune responses induced by MVA is essential for the design of vaccine vectors and for anticipating potential adverse interactions between naturally acquired and vaccine-induced immune responses. Here we report on innate immune sensing of MVA and cytokine responses in human THP-1 cells, primary human macrophages and mouse bone marrow-derived macrophages (BMDMs). The innate immune responses elicited by MVA in human macrophages were characterized by a robust chemokine production and a fairly weak pro-inflammatory cytokine response. Analyses of the cytokine production profile of macrophages isolated from knockout mice deficient in Toll-like receptors (TLRs) or in the adapter molecules MyD88 and TRIF revealed a critical role for TLR2, TLR6 and MyD88 in the production of IFNbeta-independent chemokines. MVA induced a marked up-regulation of the expression of RIG-I like receptors (RLR) and the IPS-1 adapter (also known as Cardif, MAVS or VISA). Reduced expression of RIG-I, MDA-5 and IPS-1 by shRNAs indicated that sensing of MVA by RLR and production of IFNbeta and IFNbeta-dependent chemokines was controlled by the MDA-5 and IPS-1 pathway in the macrophage. Crosstalk between TLR2-MyD88 and the NALP3 inflammasome was essential for expression and processing of IL-1beta. Transcription of the Il1b gene was markedly impaired in TLR2(-/-) and MyD88(-/-) BMDM, whereas mature and secreted IL-1beta was massively reduced in NALP3(-/-) BMDMs or in human THP-1 macrophages with reduced expression of NALP3, ASC or caspase-1 by shRNAs. Innate immune sensing of MVA and production of chemokines, IFNbeta and IL-1beta by macrophages is mediated by the TLR2-TLR6-MyD88, MDA-5-IPS-1 and NALP3 inflammasome pathways. Delineation of the host response induced by MVA is critical for improving our understanding of poxvirus antiviral escape mechanisms and for designing new MVA vaccine vectors with improved immunogenicity.

Download full-text


Available from: Carmen Elena Gomez, Oct 03, 2015
24 Reads
  • Source
    • "(Adamo et al., 2004) and that the two adaptor molecules MyD88 and TRIF divide TLR signaling pathways. Furthermore, caspase recruitment domain adaptorinducing interferon- (Cardif) is a crucial adaptor molecule in the signaling cascade of RIG-I–like receptors in antiviral responses such as against MVA (Delaloye et al., 2009). We therefore attempted to induce BALT in mice deficient for one (Myd88 / , Trif / , or Cardif / ) or two (Myd88 / Trif / ) of these adaptors. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Ectopic lymphoid tissue, such as bronchus-associated lymphoid tissue (BALT) in the lung, develops spontaneously at sites of chronic inflammation or during infection. The molecular mechanisms underlying the neogenesis of such tertiary lymphoid tissue are still poorly understood. We show that the type of inflammation-inducing pathogen determines which key factors are required for the formation and maturation of BALT. Thus, a single intranasal administration of the poxvirus modified vaccinia virus Ankara (MVA) is sufficient to induce highly organized BALT with densely packed B cell follicles containing a network of CXCL13-expressing follicular DCs (FDCs), as well as CXCL12-producing follicular stromal cells. In contrast, mice treated with P. aeruginosa (P.a.) develop BALT but B cell follicles lack FDCs while still harboring CXCL12-positive follicular stromal cells. Furthermore, in IL-17-deficient mice, P.a.-induced BALT largely lacks B cells as well as CXCL12-expressing stromal cells, and only loose infiltrates of T cells are present. We show that Toll-like receptor pathways are required for BALT induction by P.a., but not MVA, and provide evidence that IL-17 drives the differentiation of lung stroma toward podoplanin-positive CXCL12-expressing cells that allow follicle formation even in the absence of FDCs. Taken together, our results identify distinct pathogen-dependent induction and maturation pathways for BALT formation.
    Journal of Experimental Medicine 03/2014; 211(4). DOI:10.1084/jem.20131737 · 12.52 Impact Factor
  • Source
    • "Since mda5 has been described as a RNA recognizing receptor, it should principally not be involved in adenovirus recognition ( Kawai & Akira 2008 ). In the literature, however, another publication concerning a mda5-dependent induction of an immune response after infection of monocytes with a DNA virus (vaccinia virus modified Ankara, MVA) was found ( Delaloye et al. 2009 ). The exact mechanism of mda5-induced immune response could not be clarified in that study. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Methods for human skin gene therapy requires efficient and stable introduction of genes into skin cells. Transient cutaneous gene therapy is an attractive approach in the treatment of skin diseases. The 'Achilles heel' of adenoviral gene therapy is its immunogenicity and many aspects of adenovirus induced cutaneous immune reaction still remain unanswered, particularly the role of keratinocytes. Therefore, human keratinocytes were transfected with adenoviral DNA and cytokine expression was analyzed. Moreover, adenoviral transduction of full-skin was performed ex vivo and in vivo. We observed cytokine induction after cytoplasmatic internalization of adenoviral DNA into epidermal cells. Inhibition of AIM2, NALP3, DAI or mda5 downregulated the cytokine response. Transduction of immunocompetent mice led to a detectable transgene expression for 12 days. Re-application of the vector led to a decrease in intensity and duration of transgene expression limited to 4 days and an increased cytokine expression. In contrast, immunodeficient mice showed a reduced expression of cytokines after DNA internalization. AIM2, NALP3, DAI and mda5 are essential in the induction of an innate immune response towards adenoviral DNA. This immune reaction leads to a decrease in transduction efficiency of the vector after re-application and modulation of these receptor systems stabilizes transgene expression.
    SpringerPlus 12/2013; 2(1):234. DOI:10.1186/2193-1801-2-234
  • Source
    • "According to this, it has been previously reported that the total number of cells in the lungs of mice immunized intranasally with a VACV A46R deletion mutant was increased on day 2 post-infection compared with parental virus whereas on days 5 and 8 was reduced [37]. Since the main innate sensors of VACV vectors are TLR2 [15,16,17], TLR2-TLR6-MyD88, MDA-5/IPS-1 and NALP3 inflammasome [47] and A46R targets the TIR domain of the adaptors MyD88, Mal, TRIF and TRAM [37], our findings of enhanced production of TNF, IL-6 and IL-8 in conjunction with an increase in the magnitude of CD4 and CD8 T cell immune responses to HIV antigens and an enhanced gp120-specific humoral response, reveal that A46R plays an important role as immune modulator. This observation, in combination with the biochemical data on the mode of action of A46, establishes the immunological role of VACV A46R on T and B cell responses. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Viruses have developed strategies to counteract signalling through Toll-like receptors (TLRs) that are involved in the detection of viruses and induction of proinflammatory cytokines and IFNs. Vaccinia virus (VACV) encodes A46 protein which disrupts TLR signalling by interfering with TLR: adaptor interactions. Since the innate immune response to viruses is critical to induce protective immunity, we studied whether deletion of A46R gene in a NYVAC vector expressing HIV-1 Env, Gag, Pol and Nef antigens (NYVAC-C) improves immune responses against HIV-1 antigens. This question was examined in human macrophages and in mice infected with a single A46R deletion mutant of the vaccine candidate NYVAC-C (NYVAC-C-ΔA46R). The viral gene A46R is not required for virus replication in primary chicken embryo fibroblast (CEF) cells and its deletion in NYVAC-C markedly increases TNF, IL-6 and IL-8 secretion by human macrophages. Analysis of the immune responses elicited in BALB/c mice after DNA prime/NYVAC boost immunization shows that deletion of A46R improves the magnitude of the HIV-1-specific CD4 and CD8 T cell immune responses during adaptive and memory phases, maintains the functional profile observed with the parental NYVAC-C and enhances anti-gp120 humoral response during the memory phase. These findings establish the immunological role of VACV A46R on innate immune responses of macrophages in vitro and antigen-specific T and B cell immune responses in vivo and suggest that deletion of viral inhibitors of TLR signalling is a useful approach for the improvement of poxvirus-based vaccine candidates.
    PLoS ONE 09/2013; 8(9):e74831. DOI:10.1371/journal.pone.0074831 · 3.23 Impact Factor
Show more